1. Field of the Invention
This invention relates to a connector device which is used for connection of PLC (programmable logic controller) units in an electronic device.
2. Description of the Related Art
An electronic device, such as an FA (factory automation) device, is known which includes two or more box-type modules called PLC (programmable logic controller) units arrayed in a row and connected together. In the PLC units, functional electronic circuits are incorporated respectively. The PLC units are arrayed in a row and connected together in order to construct the electronic device (or the FA device) which provides a desired function.
Each PLC unit is provided with connectors each including connection terminals. For example, the methods of connection of PLC units according to the related art may be classified into a stacking structure method and a back-board structure method.
FIG. 1 is a diagram for explaining a stacking structure method according to the related art. As illustrated in FIG. 1, in this method, a connector 112 is formed on the side of each of the PLC units 111, and the PLC units 111 are arranged side by side in the direction indicated by the arrow A1 in FIG. 1. Two adjacent ones of the PLC units 111 are detachably connected to each other by means of the connector 112. All of the PLC units 111 are connected together to construct an FA device providing a desired function.
In the case of the stacking structure method, if the FA device is large in size, the number of PLC units 111 arranged in the FA device increases. If a failure of the PLC unit located in the middle of the PLC unit array arises, it is difficult to remove the defective PLC unit from the PLC unit array and replace it with a new PLC unit, and such replacement work requires some time and effort.
FIG. 2 is a diagram for explaining a back-board structure method according to the related art. As illustrated in FIG. 2, in this method, a connector is formed on the back surface of each of PLC units 121, and connectors are formed on a back board 122 which is arranged on the back of the PLC units 121. The connectors on the back surfaces of the PLC units 121 and the connectors on the back board 122 are respectively connected together to construct the FA device in which the PLC units are connected together. By moving one of the PLC units 121 in the direction indicated by the arrow A2 in FIG. 2, the PLC unit may be detached from the back board 122.
In the case of the back-board structure method, the number of PLC units 121 that can be arranged in the FA device depends on the size of the back board 122 and is restricted. The back-board structure method has a problem in that the extendibility of PLC units is limited which puts restrictions on the advantage of using the PLC units 121.
As an electronic device according to the related art, Japanese Patent No. 3579803 discloses an input/output module which can be located on a support rail and used for connection of bus terminal blocks.